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Synfacts 2014; 10(1): 0057
DOI: 10.1055/s-0033-1340438
Metal-Catalyzed Asymmetric Synthesis and Stereoselective Reactions
© Georg Thieme Verlag Stuttgart · New York

Pd-Catalyzed Asymmetric Ring Opening of Azabenzonorbornadienes

Contributor(s):
Hisashi Yamamoto
,
Sukalyan Bhadra
Huang K.-L, Guo C, Cheng L.-J, Xie L.-G, Zhou Q.-L, Xu X.-H, * Zhu S.-F. * Nankai University, Tianjin, P. R. of China
Enantioselective Palladium-Catalyzed Ring-Opening Reaction of Azabenzonorbornadienes with Methyl 2-Iodobenzoate: An Efficient Access to cis-Dihydrobenzo[c]phenanthridinones.

Adv. Synth. Catal. 2013;
355: 2833-2838
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Further Information

Publication History

Publication Date:
13 December 2013 (online)

 
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Key words

asymmetric ring opening - azabenzonorbornadienes - chiral spiro ligands - palladium

Significance

In the presence of electron-rich chiral spirophosphine ligands, I2 as key additive, and zinc powder as reducing agent, Pd(MeCN)2Cl2 efficiently catalyzes the ring opening of azabenzonorbornadiene with various 2-iodobenzoates. The resulting enantioenriched cis-dihydrobenzo[c]phenanthridinones serve as core structure of numerous optically active natural products.


 

Comment

The use of easily available organic halides instead of organometallic reagents and the construction of fused ring systems with multiple stereocenters via the tandem asymmetric ring-opening–cyclization process make the strategy remarkably efficient. A direct application of the present methodology was demonstrated via the concise total synthesis of (+)-chelidonine.


 

 


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